N,N-di-(hydroxybenzyl)-trimethylene diaminediacetic acids

ABSTRACT

A novel chelating agent having the formula ##STR1## in whichA. EACH OF X 1 , X 2 , X 3 , and X 4  is a member selected from the group consisting of (i) hydrogen; (ii) an alkyl group having 1-4 carbon atoms; (iii) --CN; (iv) --So 3  M 1  ; (v) --COOM 1  ; (vi) --OM 3  ; (vii) --NO 2  ; (viii) --OH; and (ix) ##STR2## in which each of R 1  and R 2  is an alkyl group having 1-4 carbon atoms; 
     B. each of M 1 , M 2 , M 3 , and M 4  is a member selected from the group consisting of (i) a hydrogen ion; (ii) an alkali metal ion; (iii) one-half an alkaline earth metal ion; and (vi) an ammonium ion having the formula ##STR3## in which each of R 3 , R 4 , R 5 , and R 6  is a member selected from the group consisting of (A) hydrogen; (B) an alkyl group having 1-4 carbon atoms; and (C) a hydroxyalkyl group having 1-4 carbon atoms; and 
     C. Z is a member selected from the group consisting of (i) hydrogen; and (ii) hydroxyl.

BACKGROUND OF THE INVENTION

This invention is in the field of chelating compounds and chelates ofsaid compounds with metallic ions including iron ions, copper ions,cobalt ions, manganese ions, chromium ions, nickel ions, zinc ions,cadmium ions, molybdenum ions, lead ions, and the like.

More particularly this invention is in the field of; (I) a chelatingagent (chelating compound) having the formula ##STR4## in which R₁through R₆, M₁ through M₄, Z, and X₁ through X₄ are defined in theSummary of this invention, infra; and (II) chelates of said chelatingagent with metallic ions including iron(III) and iron(II) ions.

The following U.S. Patents teach chelating compounds and chelates whichare of interest:

    ______________________________________                                        U.S. Pat. No.                                                                             Class         Inventor(s)                                         ______________________________________                                        Re. 23,904* 260/518       Bersworth                                           2,624,757   260/518       Bersworth                                           2,624,760   260/519       Bersworth                                           2,824,128   260/519       Dexter                                              2,967,196   260/507       Kroll et al                                         3,038,793   71/1          Kroll et al                                         3,110,679   252/152       Rubin                                               3,632,637   260/519       Martell                                             3,742,002   260/439R      Ohlson et al                                        3,758,540   260/439R      Martell                                             3,780,099   260/534E      Scanlon et al                                       3,780,100   260/534E      Scanlon et al                                       ______________________________________                                         *Re. 23,904 is a reissue of U.S. Pat. No. 2,624,757                      

SUMMARY OF THE INVENTION

In summary, this invention is directed to a compound (a chelating agent)having the formula ##STR5## in which a. each of X₁, X₂, X₃, and X₄ is amember selected from the group consisting of (i) hydrogen; (ii) an alkylgroup having 1-4 carbon atoms; (iii) --CN; (iv) --SO₃ M₁ ; (v) --COOM₁ ;(vi) --OM₃ ; (vii) --NO₂ ; (viii) --OH; and (ix) ##STR6## in which eachof R₁ and R₂ is an alkyl group having 1-4 carbon atoms;

b. each of M₁, M₂, M₃, and M₄ is a member selected from the groupconsisting of (i) hydrogen ion; (ii) an alkali metal ion; (iii) 1/2 analkaline earth metal ion; and (vi) an ammonium ion having the formula##STR7## in which each of R₃, R₄, R₅, and R₆ is a member selected fromthe group consisting of (A) hydrogen; (B) an alkyl group having 1-4carbon atoms; and (C) a hydroxyalkyl group having 1-4 carbon atoms; and

c. Z is a member selected from the group consisting of (i) hydrogen; and(ii) hydroxyl. This invention is also directed to a metal (e.g.,iron(III) or iron(II)) chelate of the above-described chelating agent.

The compound of this Summary in which: (a) each of X₁, X₂, X₃, and X₄ ishydrogen; (b) each of M₁, M₂, M₃, and M₄ is hydrogen or sodium; and (c)Z is hydrogen or hydroxyl is also especially useful; said compound canbe designated "Compound S-1".

DESCRIPTION OF PREFERRED EMBODIMENTS

In preferred embodiments this invention is directed to an iron chelateof the compound (chelating agent) of the above Summary. Said ironchelate can be an iron(III) chelate or an iron(II) chelate of saidchelating agent.

In another preferred embodiment ("Embodiment A") this invention isdirected to a compound (a chelating agent) having the formula ##STR8##in which a. each of X₁ and X₂ is a member selected from the groupconsisting of (i) hydrogen; (ii) an alkyl group having 1-4 carbon atoms;(iii) --CN; (iv) --SO₃ M₁ ; (v) --COOM₁ ; (vi) --OM₃ ; (vii) --NO₂ ;(viii) --OH; and (ix) ##STR9## in which each of R₁ and R₂ is an alkylgroup having 1-4 carbon atoms;

b. M is a member selected from the group consisting of (i) hydrogen;(ii) an alkali metal ion; (iii) 1/2 an alkaline earth metal ion; and(vi) an ammonium ion having the formula ##STR10## in which each of R₃,R₄, R₅, and R₆ is a member selected from the group consisting of (A)hydrogen; (B) an alkyl group having 1-4 carbon atoms; and (C) ahydroxyalkyl group having 1-4 carbon atoms; and

c. Z is a member selected from the group consisting of (i) hydrogen; and(ii) hydroxyl.

This invention is also directed to a metal chelate (e.g., iron(III) oriron(II) of the chelating agent of Embodiment A.

This invention is also directed to the compound of Embodiment A inwhich:

a. M is a hydrogen ion;

b. Z is hydrogen;

c. each of X₁ and X₂ is hydrogen.

This invention is also directed to a metal (e.g., iron(III) or iron(II))chelate of the compound of Embodiment A in which:

a. M is a hydrogen ion;

b. Z is hydrogen;

c. each of X₁ and X₂ is hydrogen.

This invention is also directed to the compound of Embodiment A inwhich:

a. M is hydrogen;

b. Z is --OH;

c. each of X₁ and X₂ is hydrogen.

This invention is also directed to a metal (e.g., iron(III) or iron(II))chelate of the compound of Embodiment A in which:

a. M is hydrogen;

b. Z is --OH;

c. each of X₁ and X₂ is hydrogen.

In another preferred embodiment ("Embodiment B") this invention isdirected to a process for preparing a first acid (a chelating agent)having the formula ##STR11## in which Z is H or OH, said processcomprising forming a resulting mixture by admixing in an inert reactionmedium selected from a first group consisting of: (i) water; (ii) analcohol selected from a second group consisting of methyl alcohol, ethylalcohol, isopropyl alcohol, and normal propyl alcohol; (iii) anadmixture of water and a member selected from the second group; (iv)acetic acid; and (v) an admixture of water and acetic acid:

a. at least one phenol having the formula ##STR12## in which each of X₁,X₂, X₃, and X₄ is a member selected (or separately selected) from thegroup consisting of (i) hydrogen; (ii) an alkyl group having 1-3 carbonatoms; (iii) --CN; (iv) --SO₃ M; (v) --SO₃ H; (vi) --COOH; (vii) --OH;(viii) --NO₂ ; and (ix) ##STR13## in which each of R₁ and R₂ is an alkylgroup having 2-4 carbon atoms; and M is an alkali metal cation, 1/2 analkaline earth metal cation, or an ammonium ion having the formula##STR14## in which each of R₃, R₄, R₅, and R₆ is hydrogen, and alkylgroup having 1-4 carbon atoms, or a hydroxyalkyl group having 1-4 carbonatoms;

b. a second acid having the formula ##STR15## in which Z is H or OH; andc. a formaldehyde source selected from the group consisting of aqueousformaldehyde, trioxane, and paraformaldehyde, and maintaining theresulting mixture at a temperature (e.g., 50°-90° C (or 60°-85° C)effective for forming the first acid for a period of time (e.g., 4-24hours (or 8-16 hours)) effective for forming the first acid, the phenol,the second acid, and the formaldehyde source being provided in amountseffective for forming the first acid and the inert solvent (inertreaction medium) being provided in an amount effective for dissolvingthe phenol. Preferred mole ratios of second acid to phenol toformaldehyde (as HCHO) are 1:2-8:2-4 (or 1:4:3).

The second acid can be fed into the system in which it will react toform the first acid as free second acid or as a salt having the formula##STR16## in which Z and M are as defined in Embodiment B. However,where feeding the second acid as said salt, the pH of the resultingmixture should be about 6 or lower (e.g., 2-6, or 1.5-5.9, or 3-6.5).Alternatively, providing the pH of the resulting mixture is about 6 orlower (e.g., 2-6, or 1.5-5.9, or 3-6.5), a salt having the formula##STR17## in which Z and M are as defined in Embodiment B can be used asa second acid source. Using either of these salts is fully equivalent tousing the second acid per se.

Where feeding free second acid per se into the system the pH of theresulting mixture should be about 6 or lower (e.g., 2-6, or 1.5-5.9, or3-6.5).

Preparation of such second acid is described in copending applicationSer. No. 630,791, filed 11 Nov. 1975 which is now U.S. Pat. No.3,988,367 assigned to W. R. Grace & Co.

The first acid can be recovered from the inert reaction medium (liquidreaction medium) in which it is formed (e.g., by centrifugation,filtration, or decantation). Alternatively, a chelate of the first acidwith iron ions (or the like) can be formed in the liquid medium in whichthe first acid was prepared by reacting the first acid with a salt suchas iron carbonate, iron sulfate, iron chloride, or the like, or withiron hydroxide. If desired, the chelate can be separated from the liquidmedium (e.g., by centrifugation, filtration, or decantation).

Alternatively, the first acid can be converted to a salt (e.g., thesodium, potassium, calcium, or ammonium salt) by reacting the first acid(e.g., in the medium in which it (the first acid) was formed) withsodium carbonate, sodium hydrogen carbonate, sodium hydroxide, ammonia,potassium carbonate, calcium hydroxide, or the like. The thus formedsalt of the first acid can be separated and recovered (e.g., byevaporation and/or centrifugation, filtration, or decantation).Alternatively, the salt while dissolved or suspended in the liquidmedium can be reacted with an iron compound such as iron sulfate, ironchloride, iron nitrate, iron acetate, or the like, to form an ironchelate. If desired, the chelate can be separated from the liquid mediumin which it was formed (e.g., by evaporation and/or centrifugation,filtration, or decantation).

More specifically, the first acid of Embodiment B can be converted to asalt having the formula ##STR18## in which M, X₁, X₂, X₃, X₄, and Z areas defined in Embodiment B by treating said first acid, preferably in anaqueous medium with an amount of an alkali metal hydroxide or carbonate,or bicarbonate, or an alkaline earth metal hydroxide, or an ammoniumhydroxide having the formula ##STR19## in which R₃, R₄, R₅, and R₆ areas defined in Embodiment B effective for bringing the pH of the systemto about 8.5-10. At this pH all --SO₃ H groups (if any) present on thefirst acid and all --COOH groups present on the first acid will beconverted to --SO₃ M groups and --COOM groups, respectively, but anyphenolic --OH groups will remain as such (i.e., as phenolic --OHgroups).

Where the pH is adjusted to about 2-5 with an alkali metal hydroxide orcarbonate, or an alkaline earth hydroxide, or the ammonium hydroxide ofEmbodiment B, the --SO₃ H groups, if any, present on the first acid willbe converted to --SO₃ M groups, but --COOH groups and phenolic --OHgroups will remain unchanged (i.e., they will still be --COOH groups andphenolic --OH groups), respectively.

Where the pH is adjusted to about 12-14 with an alkali metal hydroxide,an alkaline earth hydroxide, or the ammonium hydroxide of Embodiment B,--SO₃ H, --COOH, and phenolic --OH groups present on the first acid willbe converted to --SO₃ M groups, --COOM groups, and phenolic --OM groups,respectively.

In other embodiments of the invention recited in Embodiment B:

    ______________________________________                                        1.         The phenol is                                                                  ##STR20##                                                         2.         The phenol is                                                                  ##STR21##                                                         3.         The phenol is                                                                  ##STR22##                                                         4.         The phenol is                                                                  ##STR23##                                                         5.         The phenol is                                                                  ##STR24##                                                         6.         The phenol is                                                                  ##STR25##                                                         7.         The phenol is                                                                  ##STR26##                                                         8.         The phenol is                                                                  ##STR27##                                                         9.         The phenol is                                                                  ##STR28##                                                         10.        The phenol is                                                                  ##STR29##                                                         11.        The phenol is                                                                  ##STR30##                                                         12.        The phenol is                                                                  ##STR31##                                                         13.        The phenol is                                                                  ##STR32##                                                         14.        The phenol is                                                                  ##STR33##                                                         ______________________________________                                    

In the process of Embodiment B, where using a mixture of two phenols,one having the formula ##STR34## and the other having the formula##STR35## in which X₁, X₂, and Z are as defined in the above Summarywith further condition that X₁ and X₂ are different, the product will bean admixture of three chelating compounds having the formulas: ##STR36##

Likewise where using, in the process of Embodiment B, a mixture of twophenols having the formulas ##STR37## respectively, in which X₁, X₂, X₃,X₄, and Z are as defined in the above Summary -- with the furthercondition that none of X₁, X₂, X₃, and X₄ are identical with each other-- the product will be an admixture of three chelating compounds havingthe formulas: ##STR38##

In such instance it is generally preferred (but not necessary) that thetwo phenols be mixed in about equimolar amounts.

In another preferred embodiment ("Embodiment C") this invention isdirected to a process for preparing an acid having the formula ##STR39##in which X₁, X₂, and Z are as defined in the above Summary, said processcomprising: (a) forming a first mixture by admixing an aldehyde havingthe formula ##STR40## with methyl alcohol, ethyl alcohol, isopropylalcohol, n-propyl alcohol toluene, benzene, or ethylene chloride(providing about 1.5-8.0 parts of solvent per part aldehyde); (b)forming a Schiff base having the formula ##STR41## in which X₁, X₂, andZ are as defined in the above Summary, by admixing the first mixture andan amine having the formula ##STR42## in which Z is defined in the aboveSummary to form a second mixture and heating the second mixture to itsboiling temperature for one to three hours to cause refluxing and toremove by-product water by azeotropic distillation of the water; (c)separating the Schiff base from the mother liquor in which said base wasformed; (d) reducing the Schiff base (e.g., with NaBH₄, LiAlH₄, H₂ /Pd,or the like) to form a substituted amine having the formula ##STR43## inwhich X₁, X₂, and Z are as defined in the Summary above; (3) forming anitrile having the formula ##STR44## in which X₁, X₂, and Z are asdefined in the above Summary, by admixing said substituted amine withglycolonitrile in a solvent such as methyl alcohol, ethyl alcohol,isopropyl alcohol, or a mixture of at least one of said alcohols withwater (providing about 1.5 to 3.0 parts of alcohol per part of amine) toform a third mixture with glycolonitrile (preferably providing 1.9-2.1moles of glycolonitrile per mole of amine), and separating the resultingnitrile from the mother liquor in which said nitrile was formed(alternatively, 1 mole of formaldehyde plus 1 mole of HCN can be used inplace of each mole of glycolonitrile); (f) forming an acid hydrochloridehaving the formula ##STR45## in which X₁, X₂, and Z are as defined inthe above Summary by admixing said nitrile with hydrochloric acid(preferably concentrated hydrochloric acid, and preferably using about5-20 moles of hydrochloric acid per mole of said nitrile) andmaintaining the resulting mixture of hydrochloric acid and nitrile atabout 50°-85° C for about four hours; and (g) converting theabove-mentioned acid hydrochloride to the free acid by reacting saidacid hydrochloride with a stoichiometric amount of sodium hydroxide (twomoles per mole of the acid hydrochloride). Alternatively, astoichiometric amount of another base (e.g., KOH, Ca(OH)₂, Ba(OH)₂,various ammonium hydroxides of the formula ##STR46## (in which R₁, R₂,R₃, and R₄ are defined in the above Summary), or the like) can be usedin place of sodium hydroxide. A stoichiometric amount of KOH or##STR47## is two moles per mole of acid hydrochloride, and astoichiometric amount of Ba(OH)₂ Ca(OH)₂ is one mole per mole of theacid hydrochloride.

The above-mentioned acid hydrochloride (or the corresponding free acid)can be converted to a salt by reacting it with an amount of a base(e.g., one of those listed above) effective for neutralizing the HClmoiety of the hydrochloride and for replacing the hydrogens of the--COOH groups with the cation of the base. If desired the hydrogens ofthe phenolic groups can also be replaced with the cation of such base.

Where the aldehyde in step (a) of Embodiment C is a mixture of twoaldehydes, e.g., ##STR48## the final product (salt) will comprise threechelating compounds (chelating agents) having formulas: ##STR49## inwhich M₁, M₂, M₃, M₄, and Z are as defined in the above Summary.

Each of these three species (chelating agents) present in such instancescan be identified (e.g., by gas chromotography, and the like) in thefinal product mixture without isolating the individual species from thefinal mixture.

Also, in such instances, the final product mixture can be used toprepare iron and other chelates of excellent quality -- i.e., thechelates are prepared from the final product mixture without separatingthe individual species (the three chelating agents comprising the finalproduct mixture). Such chelates of iron(III) and iron(II) ions (i.e.,chelates of mixtures of three chelating agents formed by the aboveprocedure from two aldehydes) can be used with excellent results tosupply iron to citrus trees in calcareous soil.

The identity of Z is controlled by selecting the amine which is reactedwith the aldehyde to form the desired Schiff base. Where the amine is1,3-propanediamine, Z is H, and where the amine is1,3-diamino-2-propanol, Z is OH.

The identity of M₁, M₂, M₃, and M₄ is controlled by the selection of thebase or bases used to convert the above-mentioned acid hydrochloride tothe free acid and a salt thereof. If the acid hydrochloride is treatedwith a stoichiometric amount of sodium (or potassium) hydroxide (2 molesof OH⁻ per mole of acid hydrochloride) the H's of the carboxylic andphenolic groups will not be replaced by Na or K. If the acidhydrochloride (or the free acid) is treated with an amount of base (suchas one of the bases listed above) effective for replacing the phenolicand carboxylic hydrogens with the cation of the base M₁, M₂, M₃, and M₄will become identical with the cation of said base.

DETAILED DESCRIPTION OF THE INVENTION

The chelating agents of this invention are useful for chelating elementssuch as zinc, copper, cobalt, manganese, nickel, iron, and the like.This makes them (said chelating agents) useful additives for inclusionin metal plating baths.

The metal chelates of these compounds are useful for supplying traceelements to growing plants. The iron (iron(III) and iron(II)) chelatesof these chelating agents are, as noted infra, especially useful forsupplying iron to plants growing in calcareous soil.

As noted supra, this invention is also directed to the metal chelates ofthe chelating compounds recited in the above Summary and PreferredEmbodiments. Said chelates are excellent materials for supplying traceelements (e.g., copper, manganese, cobalt) and iron to growing plants(e.g., beans, peas, soybeans, tomatoes, peppers, and the like) includingplants growing in calcareous soil. These chelating agents form chelateswhich are useful for controlling the concentration of metallic ions inelectroplating baths.

As stated supra, this invention is also directed to chelating compoundshaving the formulas recited in the above Summary and PreferredEmbodiments, said compounds being excellent materials for chelatingiron(II) and iron(III) compounds (including such iron compounds wherepresent as "rust" stains on cloth, ceramic materials, porcelain andother surfaces, and the like, thereby to provide a convenient method forremoving such stains).

In iron chlorosis (a plant malnutritional condition caused by irondeficiency) the area of a leaf between its veins is a marked yellowgreen in contrast to the dark green of the veins. In advanced irondeficiency, this contrast is lacking and instead the leaves have anivory color, the plants become partially defoliated, and as a terminalresult, die. Such iron deficiency can be caused by any of severalfactors. Some of these are: (1) an actual deficiency of iron in thesoil; (2) high manganese and copper contents of the soil; and (3) analkaline soil (pH above 7), which can be caused by a high soil contentof calcium carbonate.

Although the value of EDTA (ethylenediaminetetraacetic acid) isrecognized and utilized in agriculture and industry, the EDTA chelatesof tri- and tetravalent metal ions are unstable in neutral and alkalinesolutions, and these metal chelates hydrolyze in water to form insolublemetal hydroxides or hydrated metal oxides. The monosodium salt of theiron(III) EDTA chelate decomposes in aqueous solutions at pH 8 toiron(III) hydroxide and a soluble EDTA salt. This behavior imposes aserious limitation on the use of EDTA. The iron(III) EDTA chelate iseffective in correcting iron deficiencies in plants grown in acid soils.However, in alkaline soils, this compound is economically ineffective intreating iron deficiency. Soil scientists have established that inalkaline soils iron(III) EDTA decomposes to liberate the iron as aninsoluble iron(III) oxide or hydroxide in which form the metal ioncannot be absorbed by the root system of the plant and therefore is notavailable for plant nutrition. In order to overcome this defect ofalkaline soils, the iron chelate of hydroxyethylethylenediaminetriaceticacid has also been recommended for plant nutrition, and although it issomewhat better than the EDTA chelate, it is economically ineffectivefor correcting iron chlorosis in calcareous soils.

A primary object of this invention is to provide iron chelates which arefree of the aforedescribed deficiencies.

While the iron chelates of this invention can be applied to growingplants as an aqueous spray we prefer to apply these chelates to thesoil.

In general, normal methods of applying micronutrients are followed withour iron chelate and other chelates. Our iron chelate (and our otherchelates) can be mixed with water and applied as a liquid early in thegrowing season or applied to an absorbent earth which is subsequentlyapplied to soil either with or without other fertilizers.

Excellent results can be obtained where applying the iron chelates at arate to provide about 1 to 4 pounds of iron (reported as Fe) per acre.In certain instances lower or higher application rates may be desirable.

Because of our disclosure various other techniques for applying ironchelates to soil will be readily apparent to those skilled in the art.

A preferred technique for removing "rust" stains from a ceramic surfacewith the chelating compounds of out invention (e.g., the compoundsdisclosed in the above Summary) comprises allowing the rust coveredsurface to remain in contact with a solution of the chelating agentuntil the rust has been removed. It has been our experience that ruststains seem to differ greatly on their ease of removal. Presumably, thisis related to the manner in which the stains were deposited or formed.It has been possible to remove rust stains simply by rubbing the stainwith a 10% aqueous solution of the chelating agent on a rag or sponge.In other instances, it has been necessary to allow time for thechelating agent to act for a longer period. In these instances we canuse several applications of a solution of the chelating agent or several"spongings" can be used. In most instances, heat accelerates the rustremoval reaction.

A preferred technique for removing rust stains from cloth is to immersethe soiled cloth in an aqueous solution of our chelating agent (e.g.,0.25-10% by weight of our chelating agent) and allow the solution toremain in contact with the cloth until the stain is removed. Thistechnique is excellent for removing rust stains from a soiled garment, atowel, or the like, but is too slow for use in textile manufacturingbecause cloth manufacturers prefer to use a fixed machine speed. In thisinstance, we prefer to add the chelating agent to a scouring both wheresaid agent prevents the formation of rust stains on the cloth.

Because of our disclosure, various other techniques for removing ruststains with the compounds of our invention will be readily apparent tothose skilled in the art.

The instant invention will be better understood by referring to thefollowing specific but nonlimiting examples and procedures. It isunderstood that said invention is not limited by these examples andprocedures which are offered merely as illustrations; it is alsounderstood that modifications can be made without departing from thespirit and scope of the invention.

The examples were actually run.

The procedures, while not actually run, will illustrate certainembodiments of our invention.

EXAMPLE 1

a. 244.0 g (2.0 moles) of salicylaldehyde was dissolved in 400 ml MeOH.74.1 g (1.0 mole) of 1,3-propanediamine in 100 ml of methanol was fedinto the aldehyde over 1 hour from 20° C to reflux. After being stirredfor 21/2 hours, the reaction mixture was cooled to 10° C, and the brightyellow crystals of N,N'-disalicylidine-1,3-propanediamine (a Schiff'sbase) were filtered off. After drying in air, 277 g (98.2% yield) wereobtained.

b. 70.5 g (0.25 mole) of the above Schiff's base was reduced by addingit portionwise to 10.1 g (0.26 mole) NaBH₄ suspended in 250 ml ofisopropanol over 30 minutes from 22°-57° C. The slurry was held at50°-58° C for 11/2 hours. 150 ml of water was dripped in slowly withcooling, and the resultant thick mass was added to 2 l of water toprecipitate the white amine. After stirring for a few minutes (ca. 10-15minutes), the amine was filtered off, washed with water, and dried inair. 55.8 g (78% yield) of N,N'-di(o-hydroxybenzyl)-1,3-propanediaminewas obtained. (Other replications of step (a) and this step (step (b))were run to prepare about 5 moles ofN,N'-di(o-hydroxybenzyl)-1,3-propanediamine.)

c. 1662.0 g (4.56 moles) of N,N'-di(o-hydroxybenzyl)-1,3-propanediaminewas slurried in 6 l methanol at 50° C. 1,192 g (11.4 moles) of 54.4%glycolonitrile was added to the amine. Within 10 minutes the amine wasdissolved. The solution was held at 40°-45° C for 11/4 hours. Aftercooling for 45 minutes to 36° C, the nitrile precipitated. The productwas filtered off an hour later at 26° C and dried in air. 1,662.0 g (80%yield) of N,N'di(o-hydroxybenzyl)-1,3-propanediamine-N,N'-diacetonitrilewas obtained.

d. All of the above nitrile (4.56 moles) was dissolved in 3 l (about 36moles) concentrated HCl acid. The solution was allowed to stand 5 daysat room temperature. Some NH₄ Cl and product hydrochlorides precipitatedduring this time. Then the reaction mixture was heated to 84° C over 2hours. The mixture was cooled to room temperature over 2 hours, itsvolume was doubled with water, and its pH was adjusted to 4.0 with 50%NaOH solution. Cooling was used to keep the mixture below 50° C. Duringthe neutralization, the product hydrochlorides precipitated and weresampled. After complete neutralization with NaOH solution the slurry wasstirred overnight. The product acid was filtered off, reslurried in 6 lof water, filtered off, and dried in air. 636 g (34.6% yield)N,N'-di(o-hydroxybenzyl)-1,3-propanediamine-N,N'-diacetic acid (HBPD)was obtained. The HBPD was identified by elemental analysis, infraredspectroscopy, acid-base titration, and Cu²⁺ titration.

EXAMPLE 2

13.2 g (0.069 mole) of 1,3-propanediamine-N,N'-diacetic acid (PDDA) wasmixed with 36 g (0.38 mole) of phenol, 50 g of glacial acetic acid, and50 ml of water. To this mixture 13.4 g (0.165 mole) of 37% formaldehydedissolved in 125 ml of water was added with stirring. The pH was 2.6.The reaction mixture was left stirring unheated overnight. After twodays standing at room temperature the mixture precipitated solidproduct. Two weeks later the reaction mixture was filtered to yield 13.0g product, or 47% based on PDDA. After washing with acetic acid andacetone, the product produced a brilliantly redcolored iron chelate inhighly alkaline solutions. A gas chromotogram showed that the productwas (HBPD) -- the same product obtained in Example 1, supra.

EXAMPLE 3

37.6 g (0.4 mole) of phenol in 25 ml of methanol was mixed with 19.0 g(0.1 mole) of PDDA and 13.7 g (0.2 mole) of 44% formaldehyde in 80 ml ofH₂ O. The mixture was heated 16 hours at 61° C. The product precipitatedas white, fluffy solids. The solids were filtered off from the cooledreaction mixture, washed with methanol, and dried at 50° C. 17.0 g of91.8% product was obtained, or 38.8% yield based on PDDA. The productwas found to be HBPD as in Example 1 and had the same iron(III)chelating activity.

EXAMPLE 4

62.6 g (0.1 mole) of 39.3% disodium hexahydropyrimidine-1,3-diacetate(HYPDANa₂) solution was acidified to pH 3 with concentrated hydrochloricacid to give a solution of 19 g (0.1 mole) of PDDA, 3 g (0.1 mole) offormaldehyde, and sodium chloride. An additional 6.9 g (0.1 mole) of 44%formaldehyde was added to said solution. The whole mixture was dilutedto 100 ml with water and added to 37.6 g (0.4 mole) of phenol in 30 mlof methanol. The mixture was reacted and the product was isolated in thesame manner as in Example 3. 16.0 g of 91.8% HBPD was obtained. Thus theequivalence of neutralized HYPDANa₂ solutions and PDDA/formaldehydesolutions in the preparation of HBPD was shown.

EXAMPLE 5

The general procedure of Example 4 was repeated except that anadditional 13.8 g (0.3 mole) of 44% formaldehyde was added instead of6.9 g. The yield was 20.8 g.

EXAMPLE 6

The general procedure of Example 5 was repeated. However, in thisinstance the methanol was omitted. The product precipitated as a stickymass of soft lumps. The product mass was mixed with MeOH to get productsolids, which were filtered off and washed with water and methanol. 29.5g of 92% HBPD was obtained after drying at 50° C or a 67.5% yield basedon HYPDANa₂.

EXAMPLE 7

62.6 g (0.1 mole) of 39.3% HYPDANa₂ solution was acidified to pH 3.1-3.2with about 18 ml of concentrated hydrochloric acid and 13.8 g (0.2 mole)of 44% formaldehyde was added. The resultant solution was mixed with75.2 g (0.8 mole) of phenol and heated 16 hours at 70° C. The productwas isolated as in Example 6. 36.8 g of 92.8% HBPD was obtained, or a84.5% yield.

EXAMPLE 8

A sample of crude HBPD prepared by the general method of Example 3 wasdissolved in aqueous sodium hydroxide to produce a solution having a pHof 8.8. The solution pH was adjusted with hydrochloric acid to 6.7, andthe solution was extracted three times with ethyl ether. The aqueouslayer was acidified with concentrated hydrochloric acid to pH 4.0 toprecipitate the acid product. The precipitate was filtered off, washedwith methanol and water, and dried. An infrared spectrogram and a gaschromatogram of the product was indentical to those of the productobtained in Example 1. A copper(II) chloride titration of the product atpH 9 indicated a molecular weight of 402.3 vs. 402 theoretical. Thesedata along with a C, H, N, and O analysis established that the productwas pure HBPD. The impurity in 90-92% methanol washed HBPD productsobtained from the reaction mixtures was found to be mostly phenol, whichHBPD complexes strongly.

EXAMPLE 9

The procedure of Example 7 was repeated to prepare HBPD. However, 50%sodium hydroxide was added to the whole reaction mixture to raise the pHto 8 and dissolve the product mass. The aqueous mixture was extractedwith two 100 ml portions of ethyl ether and acidified with hydrochloricacid to pH 4 to precipitate the acid product. The product was slurriedin water and then in methanol for washing. 34.7 g of dried pure HBPD, oran 86.3% yield was obtained.

Various other solvents were found useful for extracting the reactionmixture as in Example 9. Among them are isopropyl and butyl ether;ethyl, n-butyl, and n-amyl acetate; n-hexyl, n-amyl, i-amyl, and t-amylalcohol; and ethyl and methyl isobutyl ketones.

EXAMPLE 10

A reaction mixture was prepared by admixing 62.6 g of an aqueous systemconsisting essentially of water and HYPDANa₂ and analyzing 39.3%HYPDANa₂ (0.1 mole of HYPDANa₂), 13.8 g of an aqueous formaldehydesolution analyzing 44% HCHO (0.2 mole HCHO) and 41.8 g of an aqueoussystem consisting essentially of phenol and water and analyzing 90%phenol (0.4 mole phenol). The pH of the reaction mixture was about 3.The reaction mixture was maintained at 70° C for 16 hours and thencooled to about 25° C. The pH of the cooled reaction mixture was raisedto 8 and the resultant solution was extracted with three 100 ml portionsof ethyl ether. The aqueous layer was analyzed for HBPD byspectrophotometry (at 490 nm) of the solution after converting the HBPDproduct to its iron(III) chelate. The yield in solution was 84.3% basedon HYPDANa₂ charged. In a similar run with a reaction time of eighthours the yield was 77.7%.

EXAMPLE 11

75.8 g (0.1 mole) of 34.6% disodium5-hydroxyhexahydropyrimidine-1,3-diacetate was neutralized withhydrochloric acid to about pH 3 to give a solution of 20.6 g (0.1 mole)of 1,3-diamino-2-propanol-N,N'diacetic acid, 3 g (0.1 mole) offormaldehyde, and sodium chloride. 13.8 g (0.2 mole) of 44% formaldehydewas added to the solution. The resultant mixture was reacted with 37.6 g(0.4 mole) of phenol in 35 ml of MeOH at 60° C for 16 hours. A thickwhite product slurry was obtained. The product was filtered off,slurried in MeOH, filtered, washed, and dried at 50° C. 13.2 g (32.5%yield) of N,N'-di(o-hydroxybenzyl)-1,3-diamino-2-propanol-N,N'-diaceticacid (HBPD-OL) was obtained.

EXAMPLE 12

43.2 g (0.4 mole) of m-cresol, 20.7 g (0.3 mole) of 44% CH₂ O, and 62.6g (0.1 mole) of HYPDANa₂ (neutralized to pH 3) in 150 ml of a 33%aqueous methanol solution was allowed to stand at room temperature for15 days. The product that precipitated contained 8% m-cresol afterwashing. Isolation of the product as in Example 11 yielded 32.0 g, or74% yield, of whiteN,N'-di(2-hydroxy-4-methylbenzyl)-1,3-propanediamine-N,N'-diacetic acid.

EXAMPLE 13

55.6 g (0.4 mole) of p-nitrophenol was substituted for m-cresol in thegeneral procedure of Example 12. 15 g of beige crystals were isolated.The product was identified asN,N'-di(2-hydroxy-5-nitrobenzyl)-1,3-propanediamine-N,N'-diacetic acid.

EXAMPLE 14

43.2 g (0.4 mole) of o-cresol was substituted for m-cresol in thegeneral procedure of Example 12. 20 g ofN,N'-di-(2-hydroxy-3-methylbenzyl)-1,3-propanediamine-N,N'-diacetic acidwas isolated.

EXAMPLE 15

44.0 g (0.4 mole) of resorcinol was substituted for m-cresol in thegeneral procedure of Example 12. The reaction mixture produced a deeppurple iron chelate where admixed with iron(III) chloride in a stronglyalkaline solution.

EXAMPLE 16

44.0 g (0.4 mole) of salicylic acid was substituted for m-cresol in thegeneral procedure of Example 12. The reaction mixture produced an orangeiron chelate where admixed with iron(III) chloride in a stronglyalkaline solution.

EXAMPLE 17

3,439 g of technical HBPD analyzing 90% HBPD (i.e., 7.7 moles of HBPD)was dissolved with 50% NaOH and an amount of water to produce about 5gallons of a solution having a pH of 10. 3,210 g (7.7 moles) of 39%FeCl₃ was added concurrently with additional 50% NaOH over one hour. Atotal of about 30 moles of 50% NaOH was added. The final pH of themixture was 8.2. After being stirred overnight, the mixture wasconcentrated by boiling to a thick slurry of about 4 gallons. 4one-liter portions were filtered and each residue was washed with 200 mlof water, air dried, and weighed. Recovery was 93% of theory. Analysisof the brick red product (HBPDNaFe, the iron(III) chelate of the monosodium salt of HBPD) by visible spectrophotometry at 490 nm showed anactive ingredient (said iron chelate) content of 99.6%.

EXAMPLE 18

HBPD was prepared as in Example 7. The total reaction mixture wasdiluted with 150 ml of water, the pH of the mixture was raised to 8.38with 50% NaOH, and the resultant solution was extracted with three 100ml portions of ethyl ether. To the aqueous layer was added 36.0 g (0.086mole) of 39% FeCl₃ concurrently with 50% NaOH so that the final pH was8.3. The mixture was boiled 3 hours to reduce the volume to about 200ml. The iron chelate was filtered off, washed with 50 ml of water, anddried at 60° C. 41.2 g, a 79.5% yield based on PDDA, of HBPDNaFe wasobtained. Spectrophotometric analysis showed a 92% active ingredient,and a chloride titration indicated 2.5% NaCl.

EXAMPLE 19

20.1 g (0.05 mole) of HBPD was dissolved in 300 ml of water containing 9ml of concentrated hydrochloric acid (ca. 0.1 mole). The temperature ofthe solution was brought to 73° C and 3.0 g (0.05 mole) of sponge ironwas added. The mixture was stirred 8 hours 80° C. During this timehydrogen evolved smoothly as HBPDFeH₂.2 HCl formed, but slowed down.Another 3.0 g (0.05 mole) of sponge Fe was added and heating wascontinued another 2 hours. The excess iron was filtered off and washed.12.0 g (0.15 mole) of 50% NaOH was added to the colorless filtrate togive initially a white precipitate of HBPDFeH₂ (the iron(II) chelate ofthe acid form of HBPD having two acidic hydrogens per molecule), whichdissolved to give a colorless solution of HBPDFeNaH (the iron(II)chelate of a sodium salt of HBPD having one acidic hydrogen permolecule), which quickly oxidized to HBPDFeNa. Analysis of the oxidizedsolution by spectrophotometry showed a 66.2% yield of ferrous chelate,with 26% of the HBPD remaining unreacted.

EXAMPLE 20

0.4 lb. of HBPDNaFe per tree was applied to the soil beneath ironchlorotic orange trees growing in calcareous soil (pH 8.0) in centralFlorida. Within 5 weeks, greening of the yellow chlorotic leaves wasnoted. After 15 weeks, one of the trees was visually examined and rated.82% of the marked chlorotic twigs had greened, and only about 10% of allof the tree's leaves appeared chlorotic. Such performance represents acommercially satisfactory degree of effectiveness for citrus treesgrowing in a calcareous soil of pH 8.0 and is comparable to theperformance of Chel 138 (a commercially available iron chelate effectivefor use in calcareous soil).

PROCEDURE 1

The procedure of Example 12 can be used to prepare otherring-substituted HBPD chelating agents by replacing m-cresol with anequivalent amount of a phenol such as p-N,N-dimethylaminophenol, sodiump-phenolsulfonate, p-hydroxybenzoic acid, p-cyanophenol,2,4-dimethylphenol or the like. Analogous ring-substitutedN,N'-di(o-hydroxybenzyl)-1,3-diamino-2-propanol-N,N'-diacetic acids canbe prepared by using 1,3-diamino-2-propanol-N,N'-diacetic acid insteadof PDDA.

PROCEDURE 2

The use of only 3 moles of NaOH per mole of HBPD during the preparationof ferric chelate by the general procedure of Example 17 will yield apurple precipitate of HBPDFeH (the iron(III) chelate of HBPD).

PROCEDURE 3

20.1 g (0.05 mole) of HBPD can be slurried in 300 ml of water and 13.9 g(0.05 mole) of FeSO₄.7 H₂ O can be added thereto. The HBPD will dissolveto yield colorless solution of HBPDFeH₂.H₂ SO₄. The addition of 8.0 g(0.1 mole) of 50% NaOH under nitrogen will produce a white precipitateof HBPDFeH₂ (the iron(II) chelate of HBPD). The addition of another 8.0g (0.1 mole) of 50% NaOH under nitrogen will yield a colorless solutionof HBPDFeNa₂. Removal of the nitrogen blanket will allow the rapidoxidation of the ferrous chelate to the deep wine-red ferric chelate,HBPDFeNa.

PROCEDURE 4

One mole of HBPD.2 HCl, precipitated and recovered from the hydrolysismixture of Example 1, for example, can be reacted with about 3 moles(excess) of powdered iron, one mole of FeCO₃, one equivalent of an ironoxide (such as Fe₂ O₃ and Fe₃ O₄), or one equivalent of iron hydroxideand three moles of NaOH to produce HBPDFeNa. (One equivalent of an ironcompound is an amount of that compound that will provide one mole ofiron reported as Fe.)

PROCEDURE 5

Chelating compounds having the formula ##STR50## in which M₁, M₂, M₃,M₄, Z, X₁, X₂, X₃, and X₄ are as defined in the above Summary, can beconverted to iron chelates using the general method of Examples 17, 18,or 19. Any of the resulting iron chelates can be applied to soilincluding calcareous soil in which chlorotic plants (e.g., citrus trees)are growing by using the general method of Example 20 or by spraying anaqueous solution of the iron chelate on the chlorotic plant (e.g., onthe leaves of a chlorotic tree). In each instance such application ofiron chelate will produce a very marked decrease in the chlorosis of thetreated plants.

PROCEDURE 6

Chelating compounds having the formula ##STR51## in which M₁, M₂, M₃,M₄, Z, X₁, X₂, X₃, and X₄ are as defined in the above Summary, can beused to remove iron rust stains from cloth, glass surfaces, plasticsurfaces, tile surfaces, ceramic surfaces, metal surfaces, dishes, andthe like. This (the removal of iron rusts stains) can be accomplished byplacing an aqueous solution or dispersion of the chelating compound incontact with the rust stain and allowing the chelating compound tochelate the iron rust which can then be removed (e.g., by sponging witha damp cloth or sponge or by flushing with a stream of water). In thecase of a rust stained cloth, such cloth can be soaked in an aqueoussolution (or dispersion) of the chelating compound to chelate the ironrust, and the resulting chelated iron can be washed from the cloth.

In some instances more than one treatment will be required to remove aniron rust stain from a cloth or surface.

PROCEDURE 7

A product amine having the formula ##STR52## in which Z is --H or --OHand each of X₁, X₂, X₃, and X₄ is of hydrogen, --OH, an alkyl grouphaving 1-4 carbon atoms, --CN, --SO₃ M, or --COOM in which M is ahydrogen ion, an alkali metal ion, one-half an alkaline earth metal ion,or an ammonium ion having the formula ##STR53## in which each of R₃, R₄,R₅, and R₆ is hydrogen, an alkyl group having 1-4 carbon atoms, ahydroxyalkyl group having 1-4 carbon atoms, or an alkyl group having 1-4carbon atoms can be prepared by using the general method of the firsttwo paragraphs of Example 1 wherein the method is modified by replacingthe salicylaldehyde with aldehyde(s) having the formula(s) ##STR54## Ifit is desired to have X₁ and X₂ identical with X₃ and X₄, respectively,only one aldehyde is used, otherwise two aldehydes are used.

In such method: (a) the use of 1,3-propanediamine (as in Example 1) willproduce a product amine in which Z is --H; and (b) the use of1,3-diamino-2-propanol rather than 1,3-propanediamine will produce aproduct amine in which Z is --OH.

Where using two aldehydes, a mixture of three product amines will beobtained, to wit: ##STR55##

As used herein the term "a hydroxyalkyl group having 1-4 carbon atoms"means a group such as:

    (a) --CH.sub.2 OH;   (b) --CH.sub.2 CH.sub.2 OH; ##STR56##

    (d) --CH.sub.2 CH.sub.2 CH.sub.2 OH;

As used herein the term "mole" has its generally accepted meaning --i.e., a mole of a substance is the quantity of the substance having thesame number of molecules of the substance as there are atoms of carbonin 12 g of pure ¹² C.

As used herein the term "g" means gram or grams.

As used herein the term "HBPD" meansN,N'-di(o-hydroxybenzyl)-1,3-propanediamine-N,N'diacetic acid.

As used herein the term "HYPDANa₂ " means disodiumhexahydropyrimidine-1,3-diacetate.

As used herein the term "PDDA" means 1,3-propanediamine-N,N'-diaceticacid.

As used herein the term "PDDA-OH" means1,3-diamino-2-propanol-N,N'-diacetic acid.

As used herein "HBPDNaFe" or HBPDFeNa" means the iron(III) chelate ofthe sodium salt of HBPD.

As used herein "HBPDFe₂ H₂ " means the iron(II) chelate of the acid formof HBPD.

As used herein "HBPDFeNaH" means the iron(II) chelate of the monosodiumsalt of HBPD.

As used herein the term "HBPDFeH" means the iron(III) chelate of HBPD.

As used herein the term "HBPD-OL" meansN,N'-di(o-hydroxybenzyl)-1,3-diamino-2-propanol-N,N'-diacetic acid.

As used herein the term "CH₂ O" means formaldehyde.

As used herein the term "nm" means nanometer(s).

As used herein "l" means liter(s).

As used herein "MeOH" means methyl alcohol.

We claim:
 1. A compound having the formula ##STR57## in which: a. each Xis a member selected from a first group consisting of (i) hydrogen; (ii)an alkyl group having 1-4 carbon atoms; (iii) --SO₃ M; and (iv)--COOM;b. M is a member selected from a second group consisting of (i) ahydrogen ion; (ii) an alkali metal ion; (iii) one-half an alkaline earthmetal ion; and (iv) an ammonium ion having the formula ##STR58## inwhich each of R₁, R₂, R₃, and R₄ is a member selected from a third groupconsisting of (A) hydrogen; (B) an alkyl group having 1-4 carbon atoms;and (C) a hydroxyalkyl group having 1-4 carbon atoms.
 2. The compound ofclaim 1 in which M is a hydrogen ion or a sodium ion.
 3. A compoundhaving the formula ##STR59##
 4. A compound having the formula ##STR60##in which: a. each X is a member selected from a first group consistingof (i) hydrogen; (ii) an alkyl group having 1-4 carbon atoms; (iii)--SO₃ M; and (iv) --COOM;b. M is a member selected from a second groupconsisting of (i) a hydrogen ion; (ii) an alkali metal ion; and (iii)one-half an alkaline earth metal ion; and (iv) an ammonium ion havingthe formula ##STR61## in which each of R₁, R₂, R₃, and R₄ is a memberselected from a third group consisting of (A) hydrogen; (B) an alkylgroup having 1-4 carbon atoms; and (C) a hydroxyalkyl group having 1-4carbon atoms.
 5. The compound of claim 4 in which M is a hydrogen ion ora sodium ion.
 6. A compound having the formula ##STR62##
 7. A compoundhaving the formula ##STR63##
 8. A compound having the formula ##STR64##